Serum Total Antioxidant Capacity of Epileptic Children before and after Monotherapy with Sodium Valproate, Carbamazepine, and Phenobarbital

Objectives This case-control study was carried out to compare serum total antioxidant capacity (TAC) in the newly diagnosed children with epilepsy and that of a control group of healthy children at the same age and probable effects of antiepileptic drugs (AEDs) prescription on it. Materials & Methods Overall, 130 participants (65 in each group) aged between 1 and 17 yr old were enrolled. The study was conducted in Children’s Medical Center, the Pediatrics Center of Excellence, Tehran, Iran in 2010. Serum TAC test was done for both control and patients group before AED therapy and after 3 months of monotherapy with sodium valproate, carbamazepine and phenobarbital in patients. Serum TAC values were measured based on Erel's method using an automated commercial kit. This method is based on the bleaching of the characteristic color of a more stable 2, 2’azinobis (3ethylbenzothiazoline6sulfonic acid) radical cation by antioxidants. The results were expressed in mmol Trolox equivalent/l. Results Serum TAC values were significantly lower in the patients group before drug administration [mean (SD): 1.31 (0.19) mmol/L] in comparison with the control group [mean (SD): 1.46 (0.21) mmol/L] (P<0.001). In the patient's group, no differences were found in the serum TAC before and 3 months after AED monotherapy. Conclusion Reduced serum TAC and an increased vulnerability to oxidative stress should be considered as an etiologic factor in the children with epilepsy.


Introduction
Seizures and epileptic syndromes are common in children. 10 Oxidative stress is a product of normal metabolism in the brain or abnormal insults to the brain, for example, brain hemorrhage. Brain tissue also produces a considerable amount of free oxygen and nitrogen radicals because of a large number of mitochondria. The brain also is vulnerable to free radical damage because of a considerable amount of oxidisable polyunsaturated fatty acids. Serum concentrations of enzymatic antioxidants could be measured, but these measurements are time-consuming, expensive and require complex techniques, therefore, we carried out a study to measure serum total antioxidant capacity (TAC) with a more practical method in a group of children with newly diagnosed epilepsy before therapy and to compare this capacity by that of a group of ageand sex-matched healthy controls.

Study design
We carried out this case-control study to compare serum TAC in children with newly diagnosed epilepsy (either outpatients or inpatients) and that of a group of sex-and age-matched healthy controls. The effect of anticonvulsant monotherapy on the serum TAC also was studied in children with epilepsy before and 3 months after anticonvulsant monotherapy. The study was conducted in

Blood sample collection
Blood samples were drawn by venipuncture from the antecubital vein using a disposal plastic syringe through a 23-gauge needle in the morning between 8:00 and 11:00 am. Subjects fasted for 8 h before sample collection. All children with epilepsy were at least 24 h seizure-free before the sampling time.
Samples were transferred to the laboratory within 2 h for biochemical analysis.

Biochemical analyses
Blood samples were centrifuged at 1500 × gr for 10 min, and the serum was stored at -70 °C until the We also assessed serum albumin, total bilirubin, and uric acid as nonenzymatic antioxidants in each group. Albumin and uric acid were measured spectrophotometric method (using Bromocresol green and uricase reactant, respectively). Bilirubin was measured with dichloroaniline method. All spectrophotometric assays performed on Hitachi 717 autoanalyzer.

Statistical analysis
A significant difference in the serum total antioxidant capacity between two groups was expected (power=80%, α=0.05, β=0.2). All data were reported as the means (SD). Categorical variables were analyzed by the χ 2 -test. Continuous variables were analyzed by independent sample t-test, paired sample t-test, and One Way ANOVA on ranks with pairwise multiple comparison procedures (Dunn's Method) when appropriate. A P<0.05 was considered significant. A biostatistician blinded to study groups performed the analysis.

Results
One hundred and thirty participants (65 in each group) aged 1 to 17 yr were enrolled in this study.
The serum levels of total antioxidant capacity and nonenzymatic antioxidant parameter of the participants before AED administration are shown in Table 2. TAC was significantly lower in the patients with newly diagnosed epilepsy than that of the controls (P <0.001). Serum albumin and uric acid levels were not significantly different in the patients from the control, but serum total bilirubin was significantly lower in the patients with newly diagnosed epilepsy than that of the controls (P <0.001).  months. Serum total bilirubin and uric acid were significantly different in study groups (Table 3).
There were also no significant differences in total antioxidant capacity of the patients, before and 3 months after anticonvulsant administration based on the treatment groups (Table 4).
We also measured serum albumin, serum total bilirubin and uric acid in our participants. These are well-known endogenous antioxidant molecules in the serum (10). Uric acid concentrations were higher in untreated adults with epilepsy. There were also high uric acid concentrations in patients who treated with sodium valproate monotherapy(4). In our study, uric acid concentrations were significantly higher in children treated with phenobarbital than to the controls and other treatment groups. We also found that in children who received carbamazepine, uric acid concentrations were significantly lower than to controls and sodium valproate group.
The serum uric acid concentrations were lower in the sodium valproate monotherapy group than that of the untreated group. The serum bilirubin concentration was higher in the untreated epileptics than that of the controls, and albumin was lowter in the sodium valproate group than that of the controls (5). In our study, serum albumin had no difference between treatment groups and controls.
Moreover, serum total bilirubin was significantly higher in the controls than to sodium valproate and phenobarbital groups. We have no idea for these inconsistencies between our results and previous studies, but dietary habits and age of study population could be an explanation for these differences.
Change in nonenzymatic antioxidant levels may be a protective mechanism against decreased total an- 6. Ergul Belge Kurutas The importance of antioxidants, which play the role in cellular TAC and nonenzymatic antioxidant levels of the subjects were evaluated and the assessment of lipid peroxidation as the main oxidative marker of the oxidative stress was not performed. Another limit of our study was that at the beginning of the study we lost some of our patients. Therefore, we decided to have a short follow up and we narrowed the study to a short period of 3 months after anticonvulsant administration.
In conclusion, reduced serum total antioxidant capacity and an increased vulnerability to oxidative stress should be considered in the children with